A second-round pick of the team's in 2011, Williams has battled injuries pretty much from the get-go. His latest ailment, a right knee injury, has caused him to miss practices over the last few weeks as well as both of the team's preseason games.

And unfortunately, it does not sound like he'll be making his preseason debut when the Cardinals take the field Saturday against the San Diego Chargers at University of Phoenix Stadium.

Williams, who has rushed for just 164 yards on 58 career carries, has not played enough to show enough, and it may cost him a roster spot. The team selected running backs Stepfan Taylor and Andre Ellington in the 2013 NFL Draft to go along with Rashard Mendenhall and Alfonso Smith, so it is not as if the team has no depth behind the former Virginia Tech star.

So for Williams, being out of action while the team's other four options are on the field making plays is not a good way to impress a new coaching staff.

Playing has been an issue that has dogged Williams since his rookie year, when a ruptured patella tendon suffered in the preseason opener caused him to miss the entire campaign. Then, finally healthy last year, he played in just five games before breaking his collarbone Week 5 against the St. Louis Rams.

Arians noted that he cannot say if Williams' problems are more mental than physical right now, saying, "He's the only one that can answer that," but that right now the only thing Williams can do is a little running along with work on the stationary bike.

"You can't get these reps back," Arians lamented. "He had an excellent OTAs; he started out with an excellent camp; was cutting, running.